1. Technical Field
The present disclosure relates to prevention of post-surgical adhesions and more particularly, to devices and methods for preventing the formation of such adhesions between a healing trauma site and adjacent surrounding tissue.
2. Background of Related Art
Injury, surgical incision or abrasion to the peritoneum, pleural or abdominal cavity results in an outpouring of a serosanguinous exudate. The exudate subsequently coagulates, producing fibrinous bands between abutting surfaces which can become organized by fibroblast proliferation to become collagenous adhesions. Adhesions are also known to form at bone fracture sites where jagged, irregular bone edges form in the area of the fracture. Bony spurs promote the growth of fibrous adhesions between the bone fracture surface and surrounding tissue.
Adhesion formation following surgery or trauma is generally considered to be undesirable. For example, adhesions that form in relation to intestinal surgery, e.g., bowel resection, hernia repair, etc. may cause obstruction of the intestine. Adhesions that form near the bone fracture site may reduce or hinder the normal movement of the area of repair by restricting the natural movement of tendons over the adjacent bone. Adhesions may also form in the vicinity of nerves and disrupt nerve transmissions with a resultant diminution of sensory or motor function.
Various methods and substances have been used in the hope of preventing post-operative adhesions. Certain drugs and surfactants have been suggested. For example, U.S. Pat. No. 4,911,926 is directed to adhesion prevention by application of aqueous and non-aqueous compositions of a polyoxyalkylene block copolymer to injured areas of the peritoneal or pleural cavity or organs situated therein subsequent to surgical injury.
Another approach to adhesion prevention involves application of a physical barrier at the area of surgical injury. U.S. Pat. No. 4,674,488 is directed to interposing a barrier layer of soft biological tissue, such as collagen, collagen-fabric films, collagen membranes, or reconstituted collagen or Dacron.RTM. mesh, at the interface of a bone fracture and the surrounding tissue. U.S. Pat. No. 4,603,695 is directed to a molded adhesion barrier of a biodegradable polymer such as polyester, collagen, amino acid polymers and chitin placed where there is a possibility of adhesion setting in.
Other materials have also been used to form physical barriers in an attempt to prevent adhesions, including silicone elastomers, gelatin films and knit fabrics of oxidized regenerated cellulose (hereinafter ORC). In some cases, it is suggested that heparin, heparinoid, or hexuronyl hexosaminogly can be incorporated into a matrix of ORC fabric or other matrices of hyaluronic acid, cross-linked and uncross-linked collagen webs, synthetic resorable polymers, gelatin films, absorbable gel films, oxidized cellulose fabrics and films which are fabricated into a form that is said to be drapable, conformable and adherent to body organs and substantially absorbable within 30 days. See, e.g., U.S. Pat. No. 4,840,626 or EPA Pub. No. 0 262 890 or EPA Pub. No. 0 372 969.
Alginate and chitosan have been used in an attempt to prevent adhesions, cause hemostasis, or to fill wounds. For example, U.S. Pat. No. 5,266,326 describes in situ modification of alginate, i.e., modification while in the intra-articular space to prevent adhesions formed post-operatively. As discussed therein, adhesions are prevented by simultaneous injection of alginate solution and a complexing solution into the intra-articular space following closure of the surgical site. Examples given of the complexing solution are calcium chloride, MgCl, and CaSO.sub.4. A method of achieving hemostasis in open wounds by placing chitosan, in liquid or powder form, in contact with the wound is described in U.S. Pat. No. 4,394,373. Wound filling gel-like compositions made of chitosan and hydrocolloid materials taken from locust bean gum, karaya gum, guar gum and derivatives of guar gum are described in U.S. Pat. No. 4,956,350.
Chitosan and alginate have been used together for sustained release of pharmaceutically active agents and immobilization of biologically active material. A sustained release preparation is described in European Patent Application Pub. No. 0 187 703. As discussed therein, the preparation contains chitosan, at least one anionic polymer compound which may include alginic acid, and at least one pharmaceutically active agent. U.S. Pat. No. 5,116,747 is directed to immobilization of biologically active material in capsules prepared from a water-soluble polymer and chitosan acetate. As described therein, biological cells are encapsulated, entrapped or occluded within an ionically-interacted combination of chitosan and alginate. European Patent Application Pub. No. 0 152 898 is directed to a process for encapsulation and encapsulated active material system. As described therein, cells, microorganisms, or nonbiochemicals are encapsulated by a polymer complex of the combination of an anionic polymer such as alginate and a cationic polymer such as chitosan.